1. Field of the Invention
The present invention relates to a method for fabricating a semiconductor device, and in particular relates a method for increasing a breakdown voltage of a semiconductor device.
2. Description of the Related Art
High voltage devices have been applied in various fields. Some examples of high voltage device usage include, a driver IC of a liquid crystal display, a power management IC, a power supply, a non-volatile memory, a communication circuit, and a control circuit. For the liquid crystal display, the logic circuit of the driver IC is derived under a low voltage or a medium voltage, and the liquid crystal display is derived under a high voltage. Thus, devices formed in a chip have different breakdown voltages. Therefore, the integrating capability of high voltage devices, low voltage devices, and medium voltage devices is a major issue for semiconductor device technologies.
Generally, a vertical electric field of a channel of most MOSFETs can be reduced by forming an insulator layer by a field implantation process under a gate and source/drain region. However, the method for fabricating the semiconductor device as described above results in current leakage at an edge of, or under, the source/drain region, thus reducing breakdown voltage of the device.
As such, a method for increasing breakdown voltage of a semiconductor device is needed.